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arXiv 2024年

作者： Battley, M.P. Collins, K.A. Ulmer-Moll, S. Quinn, S.N. Lendl, M. Gill, S. Brahm, R. Hobson, M.J. Osborn, H.P. Deline, A. Faria, J.P. Claringbold, A.B. Chakraborty, H. Stassun, K.G. Hellier, C. Alves, D.R. Ziegler, C. Anderson, D.R. Apergis, I. Armstrong, D.J. Bayliss, D. Beletsky, Y. Bieryla, A. Bouchy, F. Burleigh, M.R. Butler, R.P. Casewell, S.L. Christiansen, J.L. Crane, J.D. Dalba, P.A. Daylan, T. Figueira, P. Gillen, E. Goad, M.R. Günther, M.N. Henderson, B.A. Henning, T. Jenkins, J.S. Jordán, A. Kanodia, S. Kendall, A. Kunimoto, M. Latham, D.W. Levine, A.M. McCormac, J. Moyano, M. Osborn, A. Osip, D. Pritchard, T.A. Psaridi, A. Rice, M. Rodriguez, J.E. Saha, S. Seager, S. Shectman, S.A. Smith, A.M.S. Teske, J.K. Ting, E.B. Udry, S. Vines, J.I. Watson, C.A. West, R.G. Wheatley, P.J. Winn, J.N. Yee, S.W. Zhao, Y. Observatoire Astronomique de l’Université de Genève Chemin Pegasi 51 VersoixCH-1290 Switzerland Center for Astrophysics Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States Physikalisches Institut University of Bern Gesellsschaftstrasse 6 Bern3012 Switzerland Department of Physics University of Warwick Gibbet Hill Road CoventryCV4 7AL United Kingdom Centre for Exoplanets and Habitability University of Warwick Gibbet Hill Road CoventryCV4 7AL United Kingdom Facultad de Ingeniería y Ciencias Universidad Adolfo Ibáñez Av. Diagonal las Torres 2640 Peñalolén Santiago Chile Millennium Institute for Astrophysics Chile Data Observatory Foundation Chile Department of Physics and Astronomy Vanderbilt University NashvilleTN37235 United States Astrophysics Group Keele University StaffordshireST5 5BG United Kingdom Departamento de Astronomía Universidad de Chile Casilla 36-D Santiago Chile Department of Physics Engineering and Astronomy Stephen F. Austin State University 1936 North St NacogdochesTX75962 United States Instituto de Astronomía Universidad Católica del Norte Angamos 0610 Antofagasta1270709 Chile Las Campanas Observatory Carnegie Institution for Science Colina el Pino Casilla La Serena601 Chile School of Physics and Astronomy University of Leicester LeicesterLE1 7RH United Kingdom Earth and Planets Laboratory Carnegie Institution for Science 5241 Broad Branch Road NW WashingtonDC20015 United States Caltech IPAC-NASA Exoplanet Science Institute 770 S. Wilson Avenue PasadenaCA91106 United States The Observatories of the Carnegie Institution for Science 813 Santa Barbara St. PasadenaCA91101 United States Department of Astronomy and Astrophysics University of California Santa CruzCA95064 United States Department of Physics McDonnell Center for the Space Sciences Washington University St. LouisMO63130 United States Astronomy Unit Queen Mary University of London Mile End Road LondonE1 4NS United Kingdom

Context. Long-period transiting exoplanets bridge the gap between the bulk of transit- and Doppler-based exoplanet discoveries, providing key insights into the formation and evolution of planetary systems. The wider separation between these planets and their host stars results in the exoplanets typically experiencing less radiation from their host stars;hence, they should maintain more of their original atmospheres, which can be probed during transit via transmission spectroscopy. Although the known population of long-period transiting exoplanets is relatively sparse, surveys performed by the Transiting Exoplanet Survey Satellite (TESS) and the Next Generation Transit Survey (NGTS) are now discovering new exoplanets to fill in this crucial region of the exoplanetary parameter space. Aims. This study aims to characterise a new long-period transiting exoplanet by following up on a single-transit candidate found in the TESS mission. Methods. The TOI-4862 system was monitored using a combination of photometric instruments (TESS, NGTS, and EulerCam) and spectroscopic instruments (CORALIE, FEROS, HARPS, and PFS) in order to determine the period, radius, and mass of the long-period transiting exoplanet NGTS-30 b/TOI-4862 b. These observations were then fitted simultaneously to determine precise values for the properties and orbital parameters of the exoplanet, as well as the refined stellar parameters of the host star. Results. We present the discovery of a long-period (P = 98.29838±0.00010 day) Jupiter-sized (0.928±0.032 RJ;0.960±0.056 MJ) planet transiting a 1.1 Gyr old G-type star, one of the youngest warm Jupiters discovered to date. NGTS-30 b/TOI-4862 b has a moderate eccentricity (0.294+−00014010), meaning that its equilibrium temperature can be expected to vary from 274+−3046 K to 500+−5584 K over the course of its orbit. Through interior modelling, NGTS-30 b/TOI-4862 b was found to have a heavy element mass fraction of 0.23+−000506 and a heavy element enrichment (Z

关键词： Satellites

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RadioAstron Space VLBI Imaging of the jet in M87: I. Detection of high brightness temperature at 22 GHz

arXiv

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arXiv 2023年

作者： Kim, Jae-Young Savolainen, Tuomas Voitsik, Petr Kravchenko, Evgeniya V. Lisakov, Mikhail M. Kovalev, Yuri Y. Müller, Hendrik Lobanov, Andrei P. Sokolovsky, Kirill V. Bruni, Gabriele Edwards, Philip G. Reynolds, Cormac Bach, Uwe Gurvits, Leonid I. Krichbaum, Thomas P. Hada, Kazuhiro Giroletti, Marcello Orienti, Monica Anderson, James M. Lee, Sang-Sung Sohn, Bong Won Zensus, J. Anton Department of Astronomy and Atmospheric Sciences Kyungpook National University Daegu702-701 Korea Republic of Max-Planck-Institut für Radioastronomie Auf dem Hügel 69 BonnD-53121 Germany Aalto University Department of Electronics and Nanoengineering PL 15500 AaltoFI-00076 Finland Aalto University Metsähovi Radio Observatory Metsähovintie 114 KylmäläFI-02540 Finland Lebedev Physical Institute The Russian Academy of Sciences Leninsky prospekt 53 Moscow119991 Russia Moscow Institute of Physics and Technology Dolgoprudny Institutsky per. 9 Moscow141700 Russia Department of Astronomy University of Illinois at Urbana-Champaign 1002 W. Green Street UrbanaIL61801 United States Center for Data Intensive and Time Domain Astronomy Department of Physics and Astronomy Michigan State University 567 Wilson Rd East LansingMI48824 United States Sternberg Astronomical Institute Moscow State University Universitetskij pr. 13 Moscow119992 Russia INAF-Istituto di Astrofisica e Planetologia Spaziali via Fosso del Cavaliere 100 RomaI-00133 Italy CSIRO Astronomy and Space Science PO Box 76 EppingNSW1710 Australia CSIRO Astronomy and Space Science PO Box 1130 BentleyWA6102 Australia Oude Hoogeveensedijk 4 DwingelooNL-7991 PD Netherlands Faculty of Aerospace Engineering Delft University of Technology Kluyverweg 1 DelftNL-2629 HS Netherlands Mizusawa VLBI Observatory National Astronomical Observatory of Japan 2-12 Hoshigaoka Mizusawa Iwate Oshu023-0861 Japan 2-21-1 Osawa Mitaka Tokyo181-8588 Japan via Gobetti 101 Bologna40129 Italy Leibniz Institute for Agricultural Engineering and Bioeconomy Max-Eyth-Allee 100 Potsdam-BornimD-14469 Germany Korea Astronomy and Space Science Institute 776 Daedeok-daero Yuseong-gu Daejeon34055 Korea Republic of

We present results from the first 22 GHz space very-long-baseline interferometric (VLBI) imaging observations of M87 by RadioAstron. As a part of the Nearby AGN Key science Program, the source was observed in Feb 2014 at 22 GHz with 21 ground stations, reaching projected (u, v)-spacings up to ∼ 11 Gλ. The imaging experiment was complemented by snapshot RadioAstron data of M87 obtained during 2013–2016 from the AGN Survey Key science Program. Their longest baselines extend up to ∼ 25 Gλ. For all these measurements, fringes are detected only up to ∼2.8 Earth Diameter or ∼3 Gλ baseline lengths, resulting in a new image with angular resolution of ∼ 150 µas or ∼ 20 Schwarzschild radii spatial resolution. The new image not only shows edge-brightened jet and counterjet structures down to submilliarcsecond scales but also clearly resolves the VLBI core region. While the overall size of the core is comparable to those reported in the literature, the ground-space fringe detection and slightly super-resolved RadioAstron image suggest the presence of substructures in the nucleus, whose minimum brightness temperature exceeds TB,min ∼ 1012 K. It is challenging to explain the origin of this record-high TB,min value for M87 by pure Doppler boosting effect with a simple conical jet geometry and known jet speed. Therefore, this can be evidence for more extreme Doppler boosting due to a blazar-like small jet viewing angle or highly efficient particle acceleration processes occurring already at the base of the outflow. © 2023, CC BY.

关键词： Luminance

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Genetic drivers of heterogeneity in type 2 diabetes pathophysiology

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Nature 2024年第8003期627卷 347-357页

作者： Ken Suzuki Konstantinos Hatzikotoulas Lorraine Southam Henry J Taylor Xianyong Yin Kim M Lorenz Ravi Mandla Alicia Huerta-Chagoya Giorgio E M Melloni Stavroula Kanoni Nigel W Rayner Ozvan Bocher Ana Luiza Arruda Kyuto Sonehara Shinichi Namba Simon S K Lee Michael H Preuss Lauren E Petty Philip Schroeder Brett Vanderwerff Mart Kals Fiona Bragg Kuang Lin Xiuqing Guo Weihua Zhang Jie Yao Young Jin Kim Mariaelisa Graff Fumihiko Takeuchi Jana Nano Amel Lamri Masahiro Nakatochi Sanghoon Moon Robert A Scott James P Cook Jung-Jin Lee Ian Pan Daniel Taliun Esteban J Parra Jin-Fang Chai Lawrence F Bielak Yasuharu Tabara Yang Hai Gudmar Thorleifsson Niels Grarup Tamar Sofer Matthias Wuttke Chloé Sarnowski Christian Gieger Darryl Nousome Stella Trompet Soo-Heon Kwak Jirong Long Meng Sun Lin Tong Wei-Min Chen Suraj S Nongmaithem Raymond Noordam Victor J Y Lim Claudia H T Tam Yoonjung Yoonie Joo Chien-Hsiun Chen Laura M Raffield Bram Peter Prins Aude Nicolas Lisa R Yanek Guanjie Chen Jennifer A Brody Edmond Kabagambe Ping An Anny H Xiang Hyeok Sun Choi Brian E Cade Jingyi Tan K Alaine Broadaway Alice Williamson Zoha Kamali Jinrui Cui Manonanthini Thangam Linda S Adair Adebowale Adeyemo Carlos A Aguilar-Salinas Tarunveer S Ahluwalia Sonia S Anand Alain Bertoni Jette Bork-Jensen Ivan Brandslund Thomas A Buchanan Charles F Burant Adam S Butterworth Mickaël Canouil Juliana C N Chan Li-Ching Chang Miao-Li Chee Ji Chen Shyh-Huei Chen Yuan-Tsong Chen Zhengming Chen Lee-Ming Chuang Mary Cushman John Danesh Swapan K Das H Janaka de Silva George Dedoussis Latchezar Dimitrov Ayo P Doumatey Shufa Du Qing Duan Kai-Uwe Eckardt Leslie S Emery Daniel S Evans Michele K Evans Krista Fischer James S Floyd Ian Ford Oscar H Franco Timothy M Frayling Barry I Freedman Pauline Genter Hertzel C Gerstein Vilmantas Giedraitis Clicerio González-Villalpando Maria Elena González-Villalpando Penny Gordon-Larsen Myron Gross Lindsay A Guare Sophie Hackinger Liisa Hakaste Sohee Han Andrew T Hattersley Christian Herder Momoko Horikoshi Annie-Green Howard Willa Centre for Genetics and Genomics Versus Arthritis Centre for Musculoskeletal Research Division of Musculoskeletal and Dermatological Sciences University of Manchester Manchester UK. Department of Diabetes and Metabolic Diseases Graduate School of Medicine University of Tokyo Tokyo Japan. Department of Statistical Genetics Osaka University Graduate School of Medicine Suita Japan. Institute of Translational Genomics Helmholtz Zentrum München German Research Center for Environmental Health Neuherberg Germany. konstantinos.hatzikotoulas@helmholtz-munich.de. Institute of Translational Genomics Helmholtz Zentrum München German Research Center for Environmental Health Neuherberg Germany. Center for Precision Health Research National Human Genome Research Institute National Institutes of Health Bethesda MD USA. British Heart Foundation Cardiovascular Epidemiology Unit Department of Public Health and Primary Care University of Cambridge Cambridge UK. Heart and Lung Research Institute University of Cambridge Cambridge UK. Department of Epidemiology School of Public Health Nanjing Medical University Nanjing China. Department of Biostatistics and Center for Statistical Genetics University of Michigan Ann Arbor MI USA. Corporal Michael J. Crescenz VA Medical Center Philadelphia PA USA. Department of Systems Pharmacology and Translational Therapeutics University of Pennsylvania Perelman School of Medicine Philadelphia PA USA. Department of Genetics University of Pennsylvania Perelman School of Medicine Philadelphia PA USA. Programs in Metabolism and Medical and Population Genetics Broad Institute of Harvard and MIT Cambridge MA USA. Diabetes Unit and Center for Genomic Medicine Massachusetts General Hospital Boston MA USA. TIMI Study Group Division of Cardiovascular Medicine Brigham and Women's Hospital Harvard Medical School Boston MA USA. William Harvey Research Institute Barts and the London School of Medicine and Dentistry Queen Mary University of London L

Type 2 diabetes (T2D) is a heterogeneous disease that develops through diverse pathophysiological processes and molecular mechanisms that are often specific to cell type. Here, to characterize the genetic contribution to these processes across ancestry groups, we aggregate genome-wide association study data from 2,535,601 individuals (39.7% not of European ancestry), including 428,452 cases of T2D. We identify 1,289 independent association signals at genome-wide significance (P < 5 × 10) that map to 611 loci, of which 145 loci are, to our knowledge, previously unreported. We define eight non-overlapping clusters of T2D signals that are characterized by distinct profiles of cardiometabolic trait associations. These clusters are differentially enriched for cell-type-specific regions of open chromatin, including pancreatic islets, adipocytes, endothelial cells and enteroendocrine cells. We build cluster-specific partitioned polygenic scores in a further 279,552 individuals of diverse ancestry, including 30,288 cases of T2D, and test their association with T2D-related vascular outcomes. Cluster-specific partitioned polygenic scores are associated with coronary artery disease, peripheral artery disease and end-stage diabetic nephropathy across ancestry groups, highlighting the importance of obesity-related processes in the development of vascular outcomes. Our findings show the value of integrating multi-ancestry genome-wide association study data with single-cell epigenomics to disentangle the aetiological heterogeneity that drives the development and progression of T2D. This might offer a route to optimize global access to genetically informed diabetes care.

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Author Correction: Medical history predicts phenome-wide disease onset and enables the rapid response to emerging health threats

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Nature communications 2025年第1期16卷 1507页

作者： Jakob Steinfeldt Benjamin Wild Thore Buergel Maik Pietzner Julius Upmeier Zu Belzen Andre Vauvelle Stefan Hegselmann Spiros Denaxas Harry Hemingway Claudia Langenberg Ulf Landmesser John Deanfield Roland Eils Department of Cardiology Angiology and Intensive Care Medicine Deutsches Herzzentrum der Charité (DHZC) Berlin Germany. Charité - Universitätsmedizin Berlin corporate member of Freie Universität Berlin and Humboldt Universität zu Berlin Klinik/Centrum Berlin Germany. Computational Medicine Berlin Institute of Health (BIH) Charite - University Medicine Berlin Berlin Germany. Friede Springer Cardiovascular Prevention Center@Charite Charite - University Medicine Berlin Berlin Germany. Institute of Cardiovascular Sciences University College London London UK. Center for Digital Health Berlin Institute of Health (BIH) Charite - University Medicine Berlin Berlin Germany. MRC Epidemiology Unit Institute of Metabolic Science University of Cambridge Cambridge UK. Precision Health University Research Institute Queen Mary University of London and Barts NHS Trust London UK. Institute of Health Informatics University College London London UK. Institute for Medical Engineering and Science Massachusetts Institute of Technology Massachusetts USA. Pattern Recognition and Image Analysis Lab University of Münster Münster Germany. British Heart Foundation Data Science Centre London UK. Health Data Research UK London UK. National Institute for Health Research Biomedical Research Centre at University College London Hospitals London UK. Berlin Institute of Health (BIH) Charite - University Medicine Berlin Berlin Germany. DZHK (German Centre for Cardiovascular Research) Partner Site Berlin Berlin Berlin Germany. Center for Digital Health Berlin Institute of Health (BIH) Charite - University Medicine Berlin Berlin Germany. roland.eils@bih-charite.de. Health Data Science Unit Heidelberg University Hospital and BioQuant Heidelberg Germany. roland.eils@bih-charite.de.

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11 New Transiting Brown Dwarfs and Very Low Mass Stars from TESS

arXiv

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arXiv 2025年

作者： Vowell, Noah Rodriguez, Joseph E. Latham, David W. Quinn, Samuel N. Schulte, Jack Eastman, Jason D. Bieryla, Allyson Barkaoui, Khalid Ciardi, David R. Collins, Karen A. Girardin, Eric Heldridge, Ellie Kotten, Brooke Mancini, Luigi Murgas, Felipe Narita, Norio Radford, D.J. Relles, Howard M. Shporer, Avi Soares-Furtado, Melinda Strakhov, Ivan A. Ziegler, Carl Briceño, César Calkins, Michael L. Clark, Catherine A. Collins, Kevin I. Esquerdo, Gilbert A. Fajardo-Acosta, Sergio B. Fukui, Akihiko Watkins, Cristilyn N. He, Ruixuan Horne, Keith Jenkins, Jon M. Mann, Andrew W. Naponiello, Luca Palle, Enric Schwarz, Richard P. Seager, S. Southworth, John Srdoc, Gregor Swift, Jonathan J. Winn, Joshua N. Center for Data Intensive and Time Domain Astronomy Department of Physics and Astronomy Michigan State University East LansingMI48824 United States Center for Astrophysics | Harvard & Smithsonian 60 Garden St CambridgeMA02138 United States Astrobiology Research Unit Université de Liège 19C Allée du 6 Août Liège4000 Belgium Department of Earth Atmospheric and Planetary Science Massachusetts Institute of Technology 77 Massachusetts Avenue CambridgeMA02139 United States Calle Vía Láctea s/n Tenerife La Laguna38200 Spain NASA Exoplanet Science Institute Caltech/IPAC PasadenaCA91125 United States Grand Pra Observatory Les Hauderes1984 Switzerland The Thacher School 5025 Thacher Rd. OjaiCA93023 United States Department of Astronomy University of Michigan Ann ArborMI48109 United States Department of Physics University of Rome Tor Vergata Via della Ricerca Scientifica 1 RomeI-00133 Italy Max Planck Institute for Astronomy Königstuhl 17 HeidelbergD-69117 Germany INAF Osservatorio Astrofisico di Torino Via Osservatorio 20 Pino TorineseI-10025 Italy Tenerife La LagunaE-38205 Spain Tenerife La LagunaE-38206 Spain Komaba Institute for Science The University of Tokyo 3-8-1 Komaba Tokyo Meguro153-8902 Japan Astrobiology Center 2-21-1 Osawa Tokyo Mitaka181 8588 Japan Brierfield Observatory BowralNSW Australia Center for Astrophysics | Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States Department of Physics Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology CambridgeMA02139 United States Department of Astronomy University of Wisconsin-Madison 475 N. Charter St. MadisonWI53706 United States Sternberg Astronomical Institute Lomonosov Moscow State University Universitetsky Pr. 13 Moscow119234 Russia Department of Physics Engineering and Astronomy Stephen F. Austin State University 1936 North St NacogdochesTX75962 United States SOAR Telescope NSF NOIRLab Casilla

We present the discovery of 11 new transiting brown dwarfs and low-mass M-dwarfs from NASA’s TESS mission: TOI-2844, TOI-3122, TOI-3577, TOI-3755, TOI-4462, TOI-4635, TOI-4737, TOI-4759, TOI-5240, TOI-5467, and TOI-5882. They consist of 5 brown dwarf companions and 6 very low mass stellar companions ranging in mass from 25 MJ to 128 MJ. We used a combination of photometric time-series, spectroscopic, and high resolution imaging follow-up as a part of the TESS Follow-up Observing Program (TFOP) in order to characterize each system. With over 50 transiting brown dwarfs confirmed, we now have a large enough sample to directly test different formation and evolutionary scenarios. We provide a renewed perspective on the transiting brown dwarf desert and its role in differentiating between planetary and stellar formation mechanisms. Our analysis of the eccentricity distribution for the transiting brown dwarf sample does not support previous claims of a transition between planetary and stellar formation at ∼42 MJ. We also contribute a first look into the metallicity distribution of transiting companions in the range 7 − 150 MJ, showing that this too does not support a ∼42 MJ transition. Finally, we also detect a significant lithium absorption feature in one of the brown dwarf hosts (TOI-5882) but determine that the host star is likely old based on rotation, kinematic, and photometric measurements. We therefore claim that TOI-5882 may be a candidate for planetary engulfment. Copyright © 2025, The Authors. All rights reserved.

关键词： NASA

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Memory footprint reduction for the FFT-based volume integral equation method via tensor decompositions

arXiv

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arXiv 2018年

作者： Giannakopoulos, Ilias I. Litsarev, Mikhail S. Polimeridis, Athanasios G. Skoltech Center for Computational Data-Intensive Science and Engineering Skolkovo Institute of Science and Technology Moscow143026 Russia Q Bio CA94063 United States

We present a method of memory footprint reduction for FFT-based, electromagnetic (EM) volume integral equation (VIE) formulations. The arising Green's function tensors have low multilinear rank, which allows Tucker decomposition to be employed for their compression, thereby greatly reducing the required memory storage for numerical simulations. Consequently, the compressed components are able to fit inside a graphical processing unit (GPU) on which highly parallelized computations can vastly accelerate the iterative solution of the arising linear system. In addition, the element-wise products throughout the iterative solver's process require additional flops, thus, we provide a variety of novel and efficient methods that maintain the linear complexity of the classic element-wise product with an additional multiplicative small constant. We demonstrate the utility of our approach via its application to VIE simulations for the Magnetic Resonance Imaging (MRI) of a human head. For these simulations we report an order of magnitude acceleration over standard techniques. Copyright © 2018, The Authors. All rights reserved.

关键词： Fast Fourier transforms

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A census of dwarf galaxy satellites around LMC-mass galaxy NGC 2403

arXiv

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arXiv 2024年

作者： Carlin, Jeffrey L. Sand, David J. Mutlu-Pakdil, Burçin Crnojević, Denija Doliva-Dolinsky, Amandine Garling, Christopher T. Peter, Annika H.G. Brodie, Jean P. Forbes, Duncan A. Hargis, Jonathan R. Romanowsky, Aaron J. Spekkens, Kristine Strader, Jay Willman, Beth AURA/Rubin Observatory 950 North Cherry Avenue TucsonAZ85719 United States Department of Astronomy/Steward Observatory 933 North Cherry Avenue TucsonAZ85721-0065 United States Department of Physics and Astronomy Dartmouth College HanoverNH03755 United States Department of Physics & Astronomy University of Tampa 401 West Kennedy Boulevard TampaFL33606 United States Department of Physics & Astronomy Dartmouth College HanoverNH03755 United States Department of Astronomy University of Virginia 530 McCormick Road CharlottesvilleVA22904 United States CCAPP Department of Physics Department of Astronomy The Ohio State University ColumbusOH43210 United States Centre for Astrophysics and Supercomputing Swinburne University John Street HawthornVIC3122 Australia Department of Astronomy & Astrophysics University of California Santa Cruz 1156 High Street Santa CruzCA95064 United States Centre for Astrophysics and Supercomputing Swinburne University HawthornVIC3122 Australia Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States University of California Observatories 1156 High Street Santa CruzCA95064 United States Department of Physics & Astronomy San José State University One Washington Square San JoseCA95192 United States Department of Physics Engineering Physics and Astronomy Queen's University KingstonONK7L 3N6 Canada Center for Data Intensive and Time Domain Astronomy Department of Physics and Astronomy Michigan State University East LansingMI48824 United States LSST Discovery Alliance 933 North Cherry Avenue TucsonAZ85719 United States

We present the first comprehensive census of the satellite population around a Large Magellanic Cloud (LMC) stellar-mass galaxy, as part of the Magellanic Analog Dwarf Companions and Stellar Halos (MADCASH) survey. We have surveyed NGC 2403 (D = 3.0 Mpc) with the Subaru/Hyper Suprime-Cam imager out to a projected radius of 90 kpc (with partial coverage extending out to ∼ 110 kpc, or ∼ 80% of the virial radius of NGC 2403), resolving stars in the uppermost ∼2.5 mags of its red giant branch. By looking for stellar overdensities in the red giant branch spatial density map, we identify 149 satellite candidates, of which only the previously discovered MADCASH J074238+65201- dw is a bona fide dwarf, together with the more massive and disrupting satellite DDO 44. We carefully assess the completeness of our search via injection of artificial dwarf galaxies into the images, finding that we are reliably sensitive to candidates down to MV ∼ -7.5 mag (and somewhat sensitive to even fainter satellites). A comparison of the satellite luminosity function of NGC 2403 down to this magnitude limit to theoretical expectations shows overall good agreement. This is the first of a full sample of 11 Magellanic Cloud-mass host galaxies we will analyze, creating a statistical sample that will provide the first quantitative constraints on hierarchical models of galaxy formation around low-mass hosts. © 2024, CC BY.

关键词： Population statistics

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Apercal - The Apertif calibration pipeline

arXiv

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arXiv 2021年

作者： Adebahr, Björn Schulz, R. Dijkema, T.J. Moss, V.A. Offringa, A.R. Kutkin, A. van der Hulst, J.M. Frank, B.S. Vilchez, N.P.E. Verstappen, J. Adams, E.K. de Blok, W.J.G. Denes, H. Hess, K.M. Lucero, D. Morganti, R. Oosterloo, T. Pisano, D.-J. Ivashina, M.V. van Cappellen, W.A. Connor, L.D. Coolen, A.H.W.M. Damstra, S. Loose, G.M. Maan, Y. Maccagni, F.M. Mika, A. Mulder, H. Oostrum, L.C. Orrú, E. Smits, R. van der Schuur, D. van Leeuwen, J. Vohl, D. Wijnholds, S.J. Ziemke, J. Bochum Germany ASTRON Dwingeloo Netherlands CSIRO Astronomy and Space Science Sydney Australia University of Sydney Sydney Australia Cavendish Laboratory Cambridge United Kingdom Kapteyn Astronomical Institute University of Groningen Groningen Netherlands Department of Physics Virginia Tech BlacksburgVA United States Astro Space Center of Lebedev Physical Institute Profsoyuznaya Str. 84/32 Moscow117997 Russia 2 Fir Street Observatory 7925 South Africa Inter-University Institute for Data Intensive Astronomy Department of Astronomy University of Cape Town Private Bag X3 Rondebosch 7701 South Africa University of Cape Town University Private Bag Rondebosch Cape Town7701 South Africa Department of Physics and Astronomy West Virginia University White Hall Box 6315 MorgantownWV26506 United States Dept. of Electrical Engineering Chalmers University of Technology Gothenburg Sweden Anton Pannekoek Institute University of Amsterdam Postbus 94249 Amsterdam1090 GE Netherlands Rijksuniversiteit Groningen Center for Information Technology P.O. Box 11044 Groningen9700 CA Netherlands Netherlands eScience Center Science Park 140 Amsterdam1098 XG Netherlands INAF Osservatorio Astronomico di Cagliari Via della Scienza 5 CA Selargius09047 Italy

Apertif (APERture Tile In Focus) is one of the Square Kilometre Array (SKA) pathfinder facilities. The Apertif project is an upgrade to the 50-year-old Westerbork Synthesis Radio Telescope (WSRT) using phased-array feed technology. The new receivers create 40 individual beams on the sky, achieving an instantaneous sky coverage of 6.5 square degrees. The primary goal of the Apertif Imaging Survey is to perform a wide survey of 3500 square degrees (AWES) and a medium deep survey of 350 square degrees (AMES) of neutral atomic hydrogen (up to a redshift of 0.26), radio continuum emission and polarisation. Each survey pointing yields 4.6 TB of correlated data. The goal of Apercal is to process this data and fully automatically generate science ready data products for the astronomical community while keeping up with the survey observations. We make use of common astronomical software packages in combination with Python based routines and parallelisation. We use an object oriented module-based approach to ensure easy adaptation of the pipeline. A Jupyter notebook based framework allows user interaction and execution of individual modules as well as a full automatic processing of a complete survey observation. If nothing interrupts processing, we are able to reduce a single pointing survey observation on our five node cluster with 24 physical cores and 256 GB of memory each within 24h keeping up with the speed of the surveys. The quality of the generated images is sufficient for scientific usage for 44 % of the recorded data products with single images reaching dynamic ranges of several thousands. Future improvements will increase this percentage to over 80 %. Our design allowed development of the pipeline in parallel to the commissioning of the Apertif system. © 2021, CC BY.

关键词： Surveys

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Explainable AI: Definition and attributes of a good explanation for health AI

arXiv

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arXiv 2024年

作者： Kyrimi, Evangelia McLachlan, Scott Wohlgemut, Jared M. Perkins, Zane B. Lagnado, David A. Marsh, William Gimson, Alexander Shafti, Ali Ercole, Ari Banerjee, Amitava Glocker, Ben Schafer, Burkhard Gatsonis, Constantine Grosan, Crina Sent, Danielle Berman, David S. Glass, David O'Regan, Declan P. Letsios, Dimitrios Morrissey, Dylan Pisirir, Erhan Leofante, Francesco Soyel, Hamit Williamson, Jon Grieman, Keri Dube, Kudakwashe Mardsen, Max Nagendran, Myura Tai, Nigel Kostopoulou, Olga Jones, Owain Curzon, Paul Stoner, Rebecca S. Tandle, Sankalp Joshi, Shalmali Mossadegh, Somayyeh Buijsman, Stefan Miller, Tim Madai, Vince Istvan School of Electronic Engineering and Computer Science Queen Mary University of London London United Kingdom School of Nursing Midwifery and Palliative Care King's College London London United Kingdom Centre for Trauma Sciences Blizard Institute Queen Mary University of London London United Kingdom Royal London Hospital Barts Health NHS Trust London United Kingdom Department of Experiment Psychology University College London London United Kingdom Cambridge Liver Unit Addenbrooke's Hospital Cambridge University Hospitals Hills Road Box 210 Cambridge United Kingdom University of Cambridge United Kingdom Cambridge Consultants Ltd. United Kingdom Division of Anaesthesia Cambridge Centre for AI in Medicine University of Cambridge Cambridge United Kingdom Magdelene College University of Cambridge United Kingdom Institute of Health Informatics University College London London United Kingdom Department of Computing Imperial College London London United Kingdom SCRIPT Centre for IT and IP Law School of Law University of Edinburgh United Kingdom Center for Statistical Sciences School of Public Health Brown University Providence United States Research Group Artificial Intelligence HU University of Applied Sciences Utrecht Netherlands Jheronimus Academy of Data Science Tilburg University Eindhoven University of Technology s-Hertogenbosch Netherlands Centre for Theoretical Physics Queen Mary University of London London United Kingdom School of Computing Ulster University Belfast United Kingdom MRC Laboratory of Medical Sciences Imperial College London London United Kingdom Department of Informatics King's College London United Kingdom Physiotherapy Department Barts Health NHS Trust London United Kingdom Sport and Exercise Medicine Queen Mary University of London London United Kingdom School of Electronic Engineering and Computer Science Queen Mary University of London United Kingdom Department of Computing Imperial College London United Kingdom Departmen

Proposals of artificial intelligence (AI) solutions based on increasingly complex and accurate predictive models are becoming ubiquitous across many disciplines. As the complexity of these models grows, transparency and users' understanding often diminish. This suggests that accurate prediction alone is insufficient for making an AI-based solution truly useful. In the development of healthcare systems, this introduces new issues related to accountability and safety. Understanding how and why an AI system makes a recommendation may require complex explanations of its inner workings and reasoning processes. Although research on explainable AI (XAI) has significantly increased in recent years and there is high demand for XAI in medicine, defining what constitutes a good explanation remains ad hoc, and providing adequate explanations continues to be challenging. To fully realize the potential of AI, it is critical to address two fundamental questions about explanations for safety-critical AI applications, such as health-AI: (1) What is an explanation in health-AI? and (2) What are the attributes of a good explanation in health-AI? In this study, we examined published literature and gathered expert opinions through a two-round Delphi study. The research outputs include (1) a definition of what constitutes an explanation in health-AI and (2) a comprehensive list of attributes that characterize a good explanation in health-AI. © 2024, CC BY.

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Flexible x-ray source with tunable polarization and orbital angular momentum from Hermite-Gaussian laser modes driven plasma channel wakefield

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Physical Review Accelerators and Beams 2019年第7期22卷 071302-071302页

作者： B. Lei T. Teter J. W. Wang V. Yu. Kharin C. B. Schroeder M. Zepf S. G. Rykovanov Helmholtz Institute Jena Fröbelstieg 3 07743 Jena Germany Faculty of Physics and Astronomy Friedrich-Schiller-Universität Jena 07743 Jena Germany Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences 201800 Shanghai China Lawrence Berkeley National Laboratory Berkeley California 94720 USA Center for Computational and Data-Intensive Science and Engineering Skolkovo Institute of Science and Technology Moscow 121205 Russia

A plasma channel undulator/wiggler may be created through the plasma wakefield excited by the beating of several Hermite-Gaussian laser modes propagating in a parabolic plasma channel. Control over both the betatron and undulator forces is conveniently achieved by tuning the amplitude ratios, colors, and order numbers of the modes. A special structure of the undulator/wiggler field without the focusing force near the propagation axis is generated inside the plasma wakefield by matching the strengths of the fundamental and first-order Hermite-Gaussian modes. The electron beam only experiences forced undulator oscillations in such a field, which significantly improves the quality of the emitted radiation. Since the value of the undulator strength parameter could be in a wide range, less or larger than unity, it is capable of generating narrow bandwidth x-ray, as well as the synchrotronlike high-energy x/γ-ray, radiation by harmonics. Additionally, controlling the relative phases between the laser modes allows for polarization control of the plasma undulator. High-order harmonics produced from a circularly polarized plasma undulator clearly show the vortex nature and carry well-defined orbital angular momentum.

关键词： Laser wakefield acceleration Laser-plasma interactions Plasma acceleration & new acceleration techniques Plasma waves X-ray generation in plasmas

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